Process for the preparation of tetraazamacrocycles

ABSTRACT

A process for the preparation of tetraazamacrocycles of general formula (I) ##STR1## wherein n, p and q can independently be 0 or 1, comprising the following steps: 
     a): condensation of polyamines with a glyoxal derivative; 
     b): condensation of the resulting compound with an alkylating agent; 
     c): oxidation of the resulting compound with an oxidizing agent, to give a mixture of oxidated products which is submitted to 
     d): hydrolysis in acid aqueous solution, to give the compound of formula (I).

This is a division of application Ser. No. 08/878,508, filed Jun. 19,1997, now U.S. Pat. No. 5,880,281.

This invention refers to a process for the preparation oftetraazamacrocycles of general formula (I) ##STR2## wherein n, p and qcan independently be 0 or 1, comprising the following steps of Scheme 1:##STR3## wherein step a): condensation of polyamines of formula (III)with the glyoxal derivative of formula (IV), wherein Y is --OH (glyoxalhydrate) or [--SO₃ ⁻ Na⁺ ](Bertagnini's salt), in water or inwater-soluble solvents or mixture thereof, at 0-50° C., in the presenceof stoichiometric amounts or of a slight excess of calcium hydroxide, togive the compound of formula (V);

step b): condensation of the compound of formula (V) with an alkylatingagent X--CH₂ --(CH₂)_(q) --CH₂ --X, wherein q is as previously definedand X is a halogen or a sulfonic acid reactive derivative, in at leaststoichiometric amounts, in the presence of at least 2 moles of a baseselected from alkali or alkaline-earth metal carbonates per mol ofcompound (V), at 25-150° C., to give the compound of formula (II);

step c): oxidation of the compound of formula (II) with an oxidizingagent, in water or in a diphasic system constituted by water and anorganic solvent, resistant to oxidation, at 0-100° C., to give a mixtureof oxidized products which is submitted to

step d): hydrolysis in acid aqueous solution at a pH lower than 2 or ina basic aqueous solution at a pH higher than 12, at 110-200° C., to givethe compound of formula (I).

and, in particular, the process for the preparation of1,4,7,10-tetraazacyclododecane (known as Cyclen) of formula (VIII),where in the compound of formula (I) n, p and q are 0, according to thesteps of Scheme 2. ##STR4## 1,4,7,10-tetraazacyclododecane is theprecursor for the synthesis of macrocyclic chelating agents for metalions, since these chelating agents form stable complexes with such ions.

In particular the complexes with paramagnetic metal ions, especiallygadolinium ion, of such chelates are useful in the medical diagnosticfield through Magnetic Resonance Imaging (MRI), otherwise troublesomedue to the high toxicity of the free ion. Presently two contrast mediaare available on the market, Dotarem(®) and Prohance(®), two gadoliniumcomplexes whose chemical structure is based on Cyclen, while others arestill under investigation.

Therefore it is important to work out a synthetic method relying on this"building block", which is cost-effective even from an industrial pointof view.

The process of this invention uses as raw materials linear polyamines,glyoxal, alkyl dihalides, which are generally economical, and a suitableoxidizing agent.

Therefore, the synthetic process is at the same time advantageous froman economic and environmental point of view, since it does not requirethe preparation of amines tosylderivatives, commonly used in thetraditional synthesis of Richman-Atkins (see J. Am. Chem, Soc., 96,2268, 1974).

The key intermediate of the new process is the tetracyclic derivative ofgeneral formula (II): ##STR5## where n, p and q are as previouslydefined, and the two hydrogen atoms bound to the carbon atoms of thebridge can generate cis or trans configurations, according to the sizeof the tetracyclic derivative.

Particularly useful is the intermediate of formula (VII) for thepreparation of 1,4,7,10-tetraazacyclododecane.

Such products have been already described in literature. For instance inG. R. Weisman, S. C. H. Ho, V. Johnson, Tetrahedron Lett., 1980, 21,335, the synthesis of the following tetracycles (see Table 1), has beendescribed without mentioning their use, but with the aim of studying thestereochemistry of the central bond.

                  TABLE 1                                                         ______________________________________                                          n p q                                                                                              ##STR6##                                               ______________________________________                                        0 0 0                                                                          ##STR ##                                                                        - 1 0 0                                                                           ##STR8##                                                               ______________________________________                                          n p q                                                                                        ##STR9##                                                     ______________________________________                                        1 0 1                                                                          ##STR 0##                                                                       - 1 1 1                                                                           ##STR11##                                                              ______________________________________                                    

In addition the bibliographic references cite other syntheses startingfrom polyazamacrocycles and glyoxal, in aqueous solution or in dipolaraprotic solvents, such as acetonitrile, see for instance the followingpublications:

W. Choinski, R. A. Kolinski, Polysh. Pat. 101075, Chemical Abstracts.1980, 92, 94444x;

R. A. Kolinski, F. G. Riddel, Tetrahedron Lett. 1981, 22, 2217.

A principal characteristic of the compounds of formula (II), also citedin the above works, is the extraordinary stability under basic or acidhydrolytic conditions and with respect to reducing agents, differingfrom non-cyclic aminals. This stability excluded, up to now, thepossibility of using the above tetracycles as direct precursors ofpolyazamacrocycles, and in some references the use of the sametetraazamacrocycle of formula (I) is required as raw material (G. R.Weisman, S. C. H. Ho, V. Johnson, Tetrahedron Lett., 1980, 21, 335).

More recently, WO96/28432 describes a synthetic process for compound(VII), according to the following reaction scheme: ##STR12##

The structure of the intermediate of formula (IX) is different from theintermediate of formula (VI), whose synthesis has been previouslyillustrated and is part of this invention (cfr. Example 1B experimentalsection). In fact it has a structure constituted by three cycles 5,6,5(the numbers stand for the number of atoms constituting the ring of thetricyclic system).

As a matter of fact, the synthetic conditions of the compound of formula(IX) described in WO96/28432 do not correspond to those of theintermediate (VI) of this invention, which require the use of calciumhydroxide.

WO 96/28432 also states that the intermediate (VII) can be convertedinto 1,4,7,10-tetraazacyclododecane (VIII) through acid hydrolysis, forinstance with hydrobromic acid, or through heating with hydroxylamine inethanol.

The hydrolytic treatment with hydrobromic acid, disclosed in theexperimental section of WO 96/28432, appears in conflict with theteaching of literature, which indicate the unexpected stability of (II)in acid aqueous solutions (cfr. Weisman, Tetr. Lett., 1980, 21, 335).

The reaction with hydroxylamine in ethanol, according to WO 96/28432,requires the use of strong excesses of hydroxylamine as free base. Theseconditions, implementable on a laboratory scale, are not suitable for anindustrial process, due to hydroxylamine dangerousness, which requiresextremely careful handling, use and discharge.

Now, it has been surprisingly found that the compounds of formula (II),which underwent oxidation with a suitable oxidizing agent, give amixture of products which, despite of the starting compound, areconvertible into tetraazamacrocycle of formula (I) through a simplehydrolysis.

These conditions are extremely advantageous even on an industrial scale,since they can exploit ecological, economical and low-risk processes.

Therefore this invention refers to a new process for the preparation oftetraazamacrocycles of general formula (I) ##STR13## wherein n, p and qcan independently be 0 or 1, comprising the following steps of Scheme 1:##STR14## wherein step a): condensation of polyamines of formula (III)with the glyoxal derivative of formula (IV), wherein Y is --OH (glyoxalhydrate) or [--SO₃ ⁻ Na⁺ ](Bertagnini's salt), in water or inwater-soluble solvents or mixture thereof, at 0-50° C., in the presenceof stoichiometric amounts or of a slight excess of calcium hydroxide, togive the compound of formula (V);

step b): condensation of the compound of formula (V) with an alkylatingagent X--CH₂ --(CH₂)_(q) --CH₂ --X, wherein q is as previously definedand X is a halogen or a sulfonic acid reactive derivative, in at leaststoichiometric amounts, in the presence of at least 2 moles of a baseselected from alkali or alkaline-earth metal carbonates per mol ofcompound (V), at 25-150° C., to give the compound of formula (II);

step c): oxidation of the compound of formula (II) with an oxidizingagent, in water or in a diphasic system constituted by water and anorganic solvent, resistant to oxidation, at 0-100° C., to give a mixtureof oxidized products which is submitted to

step d): hydrolysis in acid aqueous solution at a pH lower than 2 or ina basic aqueous solution at a pH higher than 12, at 110-200° C., to givethe compound of formula (I).

Preferred is the process of this invention for the preparation of:

1,4,7,10-tetraazacyclotridecane, where in the compound of formula (I) nis 1 p and q are both 0;

1,4,8,11-tetraazacyclotetradecane, where in the compound of formula (I)n is 0, p is 1 and q is 0;

1,4,8,12-tetraazacyclopentadecane, where in the compound of formula (I)n is 1 p is 1 and q is 0.

Particularly preferred is the process of this invention for thepreparation of 1,4,7,10-tetraazacyclododecane (known as Cyclen) offormula (VIII), where in the compound of formula (I) n, p and q areequal to 0, according to the following scheme through the preparation ofintermediate 3H,6H-2a, 5,6,8a-octahydro-tetraazacenaphthylene of formula(VI) starting from triethylentetraamine (TETA; corresponding to thecompound of formula (III) when n=p=0) and the following preparation ofintermediate 2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthyleneof formula (VII). ##STR15##

This invention also refers to a synthetic process useful for thepreparation of tetracyclic compounds of formula (II), comprising onlysteps a) and b) of Scheme 1, according to the following Scheme 3:##STR16##

Preferred is the process for the preparation of compounds selected fromthe group constituted by:

2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylene, where n, pand q are 0 in the compound of formula (II);

7H-2a,4a,6a,9a-decahydro-tetraazacyclohept[jkl]-as-indacene, where n is1, p and q are both 0 in the compound of formula (II);

1H,6H-3a,5a,8a,10a-decahydro-tetraazapyrene, wherein is 0, p is 1 and qis 0 in the compound of formula (II);

1H,6H,9H-3a,5a,8a,11a-decahydro-tetraazacyclohepta[def]phenantrene,where n is 1, p is 1 and q is 0 in the compound of formula (II).

Particularly preferred is the synthesis of2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylene useful for thesynthesis of 1,4,7,10-tetraazacyclododecane.

Another aspect of this invention is an alternative synthesis of thecompounds of formula (II), when n is equal to q, to give the compoundsof formula (X), starting from linear diamines of formula (XI) where n isnot present, as in Scheme 4: ##STR17## comprising steps a) and b), asfrom Scheme 1 with a difference in the amounts of reactives which areadded as indicated in Scheme 4 or in slight excess.

As far as step b) is concerned, according to the process of Scheme 1 and4, and in the case q is 0, the solvent can be even 1,2-dichloroethane(also acting as reactive).

The alkylating agent in step b), as previously said, is a dihalide or adiol, in which the hydroxy groups have been derivatized as reactiveesters of sulfonic acid (for instance tosylates, mesylates, nosylates).

The alkylating agent is dosed in amounts of at least 1 mol per mol ofintermediate of formula (V), or at least 2 moles per mol of intermediateof formula (XII).

The reaction is carried out in the presence of an inorganic base,preferably an alkali metal carbonate, dosed in amounts of at least 2moles per mol of alkylating agent.

The temperature, according to the solvent and the alkylating agent, canrange between 25 and 150° C., preferably 50-80° C. Reaction time is 1-48h.

When the cyclization ends, the suspension is cooled and the insolublesalts are filtered.

The filtrate is concentrated to a residue and the compound of formula(II) or the analogous compound of formula (X) is extracted by using anapolar solvent (as hexane or toluene). The product is concentrated to asolid residue to give the compounds of formula (II) for Scheme 1 orformula (X) for Scheme 4.

For the oxidation of compounds of formula (II) and (X), according tostep c) of Scheme 1, the usual oxidizing agent cited in literature canbe used for the oxidation of aliphatic amines (J. March, AdvancedOrganic Chemistry, Wiley-Interscience), such as:

derivatives of transition metals with a high level of oxidation, such aspotassium permanganate;

derivatives of halogens with positive oxidation state, such as sodiumhypochlorite;

halogens, such as bromine and chlorine;

peroxides, such as hydrogen peroxide;

peracid salts, such as sodium persulfate;

oxygen: in acid solution and in particular in concentrated sulfuric acidsolution.

Other possibilities are the use of metal salts, such as irontrichloride, combined with oxygen.

In addition to the usual oxidizing agents, substances which are known asreducing agents can be used. These substances with respect to compounds(II) and (X) surprisingly act as oxidizing agents. A typical example isthe use of sodium bisulfite in slightly acidic or neutral solution.

Usually the oxidation is performed in water, but with certain oxidizingagents, an organic solvent can be added (for instance acetic acid withbromine), under the conditions described in literature (for instanceDeno et al., J. Am. Chem. Soc., 1968, 3502). The pH depends on theoxidizing agent: for instance, permanganate generally reacts in neutralor slightly basic solutions, while iron trichloride and oxygen react inacid or highly acid solutions.

Even temperatures and reaction times depend on the oxidizing agent. Themildest conditions involve the use of permanganate in water (1-2 h at0-10° C.), while the use of hydrogen peroxide or hypochlorite (approx.48 h, 100° C.) requires drastic conditions.

The oxidation of compounds (II) and (X) usually generates an extremelyunstable dihydroxyl derivative, bringing about a conversion into otherproducts through rearrangement reactions and other possible oxidations,as illustrated in the following Scheme 5 in the case of2a,4a,6a,8a-decahydrotetraazacyclopent[fg]acenaphthylene (VII):##STR18##

In particular, during the oxidations of compound (VII) with bromine inslightly acidic solution, the dihydroxylate derivative is converted intoa product with a dicationic structure of formula (XIII), which isisolated as perchlorate salt of formula (XIV), nearly water-insoluble,through addition of perchlorate ions to the solution of oxidation (seeExperimental Section): ##STR19##

Other salts can be prepared from compound of formula (XIV) through ionexchange processes: for instance, through elution of an aqueous solutionof compound (XIV) on a column of an anion-exchange resin (Cl⁻ form), forexample Amberlite 4200, a solution is obtained containing compound (XV)which can be isolated from isopropanol. ##STR20##

In the first oxidative step, 4 electrons play a definitive role, whilethe number of electrons which takes part into other oxidation process isunknown.

For a complete oxidation of the tetracycle intermediate, the amount ofoxidizing agent should grant the extraction of at least 4 electrons,plus a possible excess, which can be determined experimentally. Sincethe aim of the reaction is not the completion of tetracycle oxidation,but the highest production of the effective tetraazamacrocyleprecursors, it is necessary, in some case, to stop the oxidation beforethe total tetracycle disappearance.

Table 2 illustrates some examples of oxidation of2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylene to give1,4,7,10-tetraazacyclododecane.

Table 2--Preparation of 1,4,7,10-tetraazacyclododecane Through Oxidationof 2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylene in AqueousSolution

    ______________________________________                                        Oxidizing                       Oxidation                                       agent moles t (h) T (° C.) (%) Yield (%)                             ______________________________________                                        Permanganate                                                                            1.33    2       0     70      43                                      Permanganate 2 1 10 100 52                                                    Hypochlorite 6 24 80 63 38                                                    Hypochlorite 12 48 80 100 27                                                  Persulfate 2 1 0 58 33                                                        Persulfate 2.5 2 0 85 38                                                      Bromine 2.5 18 20 99  62*                                                   ______________________________________                                         *after recrystallization from toluene (1st crop)                         

The last two columns from right show the tetracycle oxidation percentageand the final yield in 1,4,7,10-tetraazacyclododecane, isolated afterhydrolysis of the mixture resulting from the final oxidation (insolubleinorganic compounds, such as manganese dioxide, are removed byfiltration).

In case of oxidation carried out under neutral or slightly basicconditions, the hydrolysis is carried out in a highly basic aqueoussolution (pH>12), at a temperature ranging from 110 to 200° C., andduring 3 and 24 h.

The isolation of 1,4,7,10-tetraazacyclododecane is carried out throughcrystallization of the same from the suitably concentrated hydrolyzedsolution.

In case of oxidation carried out in acid solution, in alternative to theconditions of basic hydrolysis, acid hydrolysis can be performed,operating for instance for 5-48 h in sulfuric acid-water, at 100-150° C.

When the acid hydrolysis is complete, the solution is alkalinized, andafter concentration, 1,4,7,10-tetraazacyclododecane is isolated throughcrystallization. The product can be recrystallized from water, tolueneor ethyl acetate.

Particularly preferred is the preparation of1,4,7,10-tetraazacyclododecane, according to the previously cited Scheme2, using bromine, as oxidizing agent in step c), in aqueous solution ata pH of 4-6, preferably 4.5, in a ratio of 2.0-3.0 moles per mol ofcompound (VII), preferably 2.5 and at a temperature of 17-30° C.

As various changes could be made in the above compositions and methodswithout departing from the scope of the invention, it is intended thatall matter contained in the above examples shall be interpreted asillustrative and not in a limiting sense.

The following gas-chromatographic method has been used to monitor thereactions (except for the compound of formula (XIII))

Equipment: gas-chromatographic unit Hewlett-Packard series 5890 II Plusequipped with self-sampling unit series 7673 and unit HP-3365

Column: silica capillary 25 m, int. diam. 0.32 mm, stationary phase CPSil 19CB, film thickness 0.2 mm (Chrompack art.7742)

Oven temperature: first isotherm at 120° C. for 5 min; ramp 15° C./min;final isotherm at 260° C. for 2 min

Injected volume: 1 mL

Detector: FID; temperature 275° C.

EXAMPLE 1

Preparation of 2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylene(CAS RN 74199-09-0) According to Scheme 1. ##STR21## A)Triethylenetetraamine hydrate

520 g of triethylenetetraamine (GC 62% % in area) are dissolved in 800mL of toluene. 80 mL of water are added under stirring, then thesolution is cooled to 25° C. and germinated with purifiedtriethylenetetraamine. The suspension is kept under stirring for 45 min.at 20° C., then cooled to 5-10° C. for 1 h. The crystallized solid isfiltered, washed with few toluene and dried at 30° C. under vacuum for 8h to give 365 g of the desired product.

Yield: 91%

Water content: 17%

GC: 97% (% in area)

B) 3H,6H-2a,5,6,8a-Octahydro-tetraazacenaphthylene (CAS RN 78695-52-0)##STR22##

To a solution of triethylenetetraamine hydrate (100 g, 0.54 mol) inwater (1 L) 80 g (1.08 mol) of calcium hydroxide are added. Thesuspension is cooled to 5° C., then a 5%-glyoxal aqueous solution (626g, 0.54 mol) is added under stirring. After 2 h the reaction is complete(no triethylenetetraamine, GC analysis). The solution is taken to 20°C., the insoluble inorganic solid is filtered and washed with water. Thefiltrate is concentrated in a rotating evaporator under vacuum to give100 g of the desired intermediate as colorless oily liquid. (GCpurity:>75%)

Note: the intermediate of formula (VI) can be purified through thepreparation of salts. For instance, 15 g (0.09 mol) of the compound (VI)are dissolved in 100 g of toluene. 5.5 g of 96% acetic acid are added.After 10 min under stirring the precipitate is filtered and washed withfew toluene and dried to 30° C. under vacuum to give 14.1 g of (V)monoacetate.

Yield: 70%.

GC:>98%

¹ H-NMR, ¹³ C-NMR, IR and MS spectra are consistent with the structure.

C) 2a,4a,6a,8a-Decahydro-tetraazacyclopent[fg]acenaphthylene (CAS RN79236-92-3)

The crude intermediate (VI) is redissolved in 1 L of DMAC. 101.4 g (0.54mol) of 1,2-dibromoethane are added. The resulting solution is dropwiseadded to a suspension constituted by anhydrous sodium carbonate (600 g)and DMAC (1 L), then heated to 100° C. When the 20-min addition ends,the suspension reacts for additional 30 min. The inorganic salts canfiltered and the filtrate is concentrated in a rotating evaporator undervacuum, up to a residue, which is dissolved to 0.5 L of hexane. Theinsoluble by-products are filtered, and the filtrate is concentrated todryness to give 48 g (0.24 mol) of the desired product.

Yield: 45%

GC: 98.5% (% in area)

¹ H-NMR, ¹³ C-NMR, IR and MS spectra are consistent with the structure.

EXAMPLE 2

Preparation of 2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthyleneAccording to Scheme 1, using 1,2-dichloroethane ##STR23##

80 g (0.48 mol) of crude 3H,6H-2a,5,6,8a-tetraazanaphthylene octahydrate(prepared according to Example 1) are dissolved in 0.4 L of1,2-dichloroethane. 100 g of anhydrous sodium carbonate are added andthe suspension is heated to 50° C. for 48 h and cooled. The insolubleproduct is filtered and the filtrate is concentrated to dryness. Thecompound of formula (VII) is extracted with 0.4 L of hexane. Theinsoluble product is filtered and the filtrate is concentrated to give31.2 g (0.16 mol) of the desired product.

Yield: 33%.

GC: 97.5% (% in area)

¹ H-NMR, ¹³ C-NMR, IR and MS spectra are consistent with the structure.

Following the procedure of the example the following tetraazacycles areprepared: ##STR24##7H-2a,4a,6a,9a-decahydro-tetraazacyclohept[jkl]-as-indacene (CAS RN74199-11-4) starting from N,N'-bis(2-aminoethyl)-1,3-propanediamine(commercial product, CAS RN 4605-14-5) ##STR25##1H,6H-3a,5a,8a,10a-decahydro-tetraazapyrene (CAS RN 72738-47-7) startingfrom N,N'-bis(3-aminopropyl)ethylenediamine (commercial product, CAS RN10563-26-5) ##STR26##1H,6H,9H-3a,5a,8a,11a-decahydro-tetraazacyclohepta[def]phenantrenestarting from N,N'bis-(3-aminopropyl)-1,3-propanediamine (commercialproduct, CAS RN 4741-99-5)

EXAMPLE 3

Preparation of 2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthyleneAccording to Scheme 4 ##STR27##

To an aqueous solution of ethylenediamine (60.1 g, corresponding to 1mol) in water (300 mL) 72.6 g (0.5 mol) of 40%-glyoxal aqueous solutionare added and kept at room temperature (25° C.) for an entire night. Thesolution is concentrated in a rotating evaporator under vacuum, up to aresidue. The solid residue is suspended in 900 mL of DMAC, 500 g ofanhydrous sodium carbonate are added and a solution of 187.87 g (1 mol)of 1,2-dibromoethane in DMAC (500 mL) is dropwise added. The suspensionis heated to 40° C. and kept under reaction for 48 h. The insolublesalts are filtered and the filtrate is concentrated in a rotatingevaporator under vacuum, up to a residue, which is added with 0.5 L ofhexane. The insoluble product is filtered and concentrated to dryness togive 38 g (0.19 mol) of the desired product.

Yield: 38%

GC: 98.0% (% in area)

¹ H-NMR, ¹³ C-NMR, IR and MS spectra are consistent with the structure.

EXAMPLE 4

Preparation of 1,4,7,10-tetraazacyclododecane Through PermanganateOxidation ##STR28##

30 g (0.15 mol) of2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylene (preparedaccording to Examples 1, 2 or 3), are dissolved in 200 mL of water. Thesolution is cooled to 0° C. and a 5%-potassium permanganate aqueoussolution (750 g of solution, 0.30 mol) is dropwise added. Then manganesedioxide is filtered on a bed of celite under vacuum. The filtrate istransferred to the autoclave, 48 g of sodium hydroxide are added and thesolution is heated to 180° C. for 24 h then cooled. The content of theautoclave is transferred to a common reactor. The suspension is heatedto ebullition, and treated with active carbon by filtering the hotsolution on a bed of celite under vacuum. The filtrate is concentratedof 50° C. under reduced pressure, to give a turbid solution which iscooled to 25° C. under stirring. After one night the crystallized solidis filtered and dried in an oven under vacuum, up to a constant weightto give 10.9 g of highly pure 1,4,7,10-tetraazacyclododecane (1st crop)(99.6%, GC), as a white needle-shaped crystalline product.

The mother liquors are concentrated to 50° C. under reduced pressure togive a turbid solution which crystallizes under the same conditions ofthe 1st crop thus giving additional 2.8 g of1,4,7,10-tetraazacyclododecane (2nd crop) (98.5%, GC).

Total yield: 52%.

¹ H-NMR, ¹³ C-NMR, IR and MS spectra are consistent with the structure.

According to the procedure described in the example the followingtetraazamacrocycles starting from the tetracycles prepared followingExample 1, 2 or 3 are prepared:

-1,4,7,10-tetraazacyclotridecane ##STR29##-1,4,8,11-tetraazacyclotetradecane ##STR30##-1,4,8,12-tetraazacyclopentadecane ##STR31##

EXAMPLE 5

Preparation of 1,4,7,10-tetraazacyclododecane through oxidation of2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylene withhypochlorite ##STR32##

30 g (0.15 mol) of2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthyhylene, dissolvedin 300 g of water, are treated with 550 g (0.89 mol) of sodiumhypochlorite (approx. 12% aqueous solution) for 24 h at 80° C. The finalsolution is cooled and hydrolyzed under conditions analogous to thosedescribed in Example 4. 9.8 g (1st and 2nd crop) of1,4,7,10-tetraazacyclododecane are obtained. Yield: 38%.

EXAMPLE 6

Preparation of 1,4,7,10-tetraazacyclododecane through oxidation of2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylene withpersulfate. ##STR33##

30 g (0.15 mol) of2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylene, dissolved in700 g of water, are treated with 620 mL of 2N NaOH. To the resultingsolution, cooled to 0 °C., are added 71.4 g (0.3 mol) of sodiumpersulfate dissolved in 700 mL of water. After 1 h the solution ishydrolyzed, following the procedure of Example 4 to give 8.7 g (0.5 mol)of 1,4,7,10-tetraazacyclododecane. Yield: 33%.

EXAMPLE 7

Preparation of 1,4,7,10-tetraazacyclododecane through oxidation of2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylene with brominein acetic buffer.

26 g (0.13 mol) of2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylene are dissolvedin 1.3 L of sodium hydroxide 2N. The solution is buffered to pH 5through addition of 300 g of acetic acid, then 43.8 g (0.27 mol) ofbromine are dropwise added and kept for 2 h at 25° C. 200 g of sodiumhydroxide are added and the solution is heated in autoclave at 150° C.for 24 h, then the solution is cooled and concentrated up to 400 mL. Theproduct crystallizes at room temperature (25° C.) for one night to give8.7 g of 1,4,7,10-tetraazacyclododecane.

Yield: 38%

EXAMPLE 8

Preparation of 1,4,7,10-tetraazacyclododecane through oxidation of2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylene with air

20 g (0.10 mol) of2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylene are dissolvedin 100 g of sulfuric acid (water content=50%). Air is bubbled into thesolution, which is heated to ebullition (T=112° C.) for 24 h, and thenis cooled. 170 g of 30%-water sodium hydroxide are slowly added and thesuspension is kept at a temperature of 17° C. for a whole night.

Crude 1,4,7,10-tetraazacyclododecane is filtered and dried in oven undervacuum. The resulting 5.6 g of crude product are redissolved in 50 mL ofwarm toluene. The insoluble salts are filtered and the filtrate isconcentrated up to a volume of 10 mL and kept at 17° C. per 2 h to give3.8 g of purified 1,4,7,10-tetraazacyclodecane.

Yield: 22%

EXAMPLE 9

Preparation of 1,4,7,10-tetraazacyclododecane through oxidation of2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylene with bromine.

1.66 kg (8.55 mol) of2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylene (preparedaccording to Examples 1 and 2) are dissolved in 15 kg of deionizedwater. 18.5 kg of 1N HCl are added up to pH 4.5, then the solution iscooled to 20° C. and 3.42 kg of bromine (21.48 mol) and 46.7 kg of 1NNaOH are dropwise added to keep pH 4.5.

After one night at room temperature 8.4 kg of NaOH are added, up to pH14. The solution is transferred to the autoclave and hydrolyzed at180-185° C. for 5.5 h then cooled to room temperature. The solution isconcentrated under reduced pressure. The resulting suspension is keptunder stirring at room temperature for 24 h, then the precipitate isfiltered. The wet solid is dried in an oven under vacuum to give1,4,7,10-tetraazacyclododecane contaminated by inorganic salts. Thesolid is suspended in 16 kg of toluene and heated under reflux, thewater is removed through azeotropic distillation and then the suspensionvolume is reintegrated with fresh toluene. The inorganic salts areremoved by filtering the hot solution, and washed with toluene preheatedat 60° C. The filtrate is concentrated up to a residual weight of 3 kg,then cooled to 17° C. for 2 h and up to 0° C. for 1 h. The crystallizedsolid is filtered and washed with few cold toluene and the product isdried at 50° C. under vacuum to give 0.9 kg (5.22 mol) of1,4,7,10-tetraazacyclododecane (GC: 99.23%). From toluene motherliquors, concentrated to 250 mL, 108 g (0.63 mol) are obtained as secondcrop.

Total yield: 68%.

EXAMPLE 10

Preparation and isolation of the compound of formula (XIV) ##STR34##

50.4 g (0.259 mol) of2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylene are dissolvedin 955 g of deionized water. 311 g of 1N HCl are added up to pH 4.5,then the solution is cooled to 20° C. and 91.44 g (0.66 mol) of bromineand 1.026 kg of 1N NaOH, are simultaneously dropwise added in order tokeep a pH of 4.5. After one night at room temperature the solution isconcentrated under reduced pressure and at 50° C. up to 1.38 kg. Then iscooled to 25° C. and 144 g of aqueous solution containing 50% w/w ofsodium perchloride monohydrate are added under stirring. After 15 h theprecipitate is filtered and washed with water. After drying in ovenunder vacuum at 50° C., 50.5 g of the product are obtained.

Yield: 50%.

Electrophoretic Method

    ______________________________________                                        Capillary:       fused silica 0.56 m × 75 mm                              Voltage: 12 kV                                                                Buffer: 0.05 M phosphate pH 4.5                                               Temperature: 40° C.                                                    Stoptime: 20 min.                                                             Detection: (UV) 200-220 nm                                                    Injection: hydrostatic (50 mbar, 3 s)                                         Sample conc.: 1 mg/mL                                                         Instrumentation: Hewlett Packard 3D HPCE                                    ______________________________________                                        Preconditioning                                                                             t (min)   action                                                  timetable: 0 flush with H.sub.2 O                                              2 flush with 0.1 M NaOH                                                       4 flush with H.sub.2 O                                                        5 flush with buffer                                                           9 start analysis                                                           ______________________________________                                        Elemental analysis                                                                         C%      H%      Cl%   N%    O%                                     calc. 30.70 4.12 18.13 14.32 32.72                                            found 30.74 4.14 18.03 14.20 32.66                                          ______________________________________                                    

EXAMPLE 11

Preparation of 1,4,7,10-tetraazacyclododecane Through Hydrolysis of theProduct of Example 10

45 g (0.115 mol) of compound (XIV) (prepared according to Example 10),are suspended in 1.1 L of water. NaOH is added up to pH 14, thesuspension is transferred to the autoclave and saponificated to 185° C.for 5.5 h. The solution is cooled to 50° C. and concentrated underreduced pressure up to 0.75 L and kept for 24 h at room temperature andfiltered. The precipitated solid is filtered and dried to give1,4,7,10-tetraazacyclododecane contaminated by inorganic salts, thenpurified through recrystallization from toluene, as described in Example9 to give 16.8 g (0.098 mol, 1st crop) of 1,4,7,10-tetraazacyclododecane(GC: 99.5%).

EXAMPLE 12

Oxidation of 2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylenewith sodium bisulfite

40 g (0.206 mol) of2a,4a,6a,8a-decahydro-tetraazacyclopent[fg]acenaphthylene are dissolvedin 500 g of water. 86 g of sodium bisulfite (0.824 mol) are added andthe solution is heated to 95° C. for 17 h then cooled to roomtemperature. NaOH is added up to 14 and then the procedure is carriedout according to Example 9 to give 15.9 g (0.093 mol) of1,4,7,10-tetraazacyclododecane (GC: 98.5%). Yield: 45%.

EXAMPLE 13

Preparation of Compound (XV) ##STR35##

4.12 g of (XIV) (see Example 10), are dissolved in 410 mL of deionizedwater. The solution is percolated on a column containing 136 mL ofAmberlite 4200 resin (Cl⁻ form), and then washed with water. The usefulfractions containing the product (TLC analysis (silicagel):eluent:chloroform:acetic acid:water=4:5:1 (v/v/v)) are collectedand concentrated at 50° C. under vacuum, up to a small volume, thenisopropanol is added. After 4 h the precipitate is filtered and washedon a filter with few isopropanol. After drying the product in an ovenunder vacuum at 50° C., 2.14 g of the desired product are obtained.

Analytical Characteristics

Water content (Karl Fischer): 11.8%

AgNo₃ (Cl⁻): 99% (calculated for the anhydrous)

What is claimed is:
 1. A process of producing a tetraazamacrocycle ofthe formula: ##STR36## comprising oxidizing a compound of the formula:##STR37## with bromine to prepare a compound of the formula ##STR38##which is hydrolyzed to yield a compound of the formula ##STR39##
 2. Acompound of the formula:
 3. A process for the preparation ofcompound(XIV) comprising adding a perchlorate salt to an aqueoussolution of compound (XIII) the end of the oxidation to give thecompound of formula (XIV)
 4. A compound of formula (XIV)
 5. A processfor the preparation of compound (XV) by eluting, an aqueous solution ofcompound (XIV) on a column of an anion-exchange resin in the Cl⁻ form togive a solution containing the compound (XV), which is thereafterisolated from isopropanol.
 6. A compound of formula (XV) ##STR40##